Waterproof sandpaper



, Patented FebJl,

azucar warnaraoor sANnrnrEn Richard Paul Garlton and Byron J.

Oakes,

St. Paul. Minn., assignors to Minnesota Mining & Manufacturing Company, St. Paul, Minn., a

lcorporation of Delaware original application January 21,1934, semi No.

Divided and this-application November 7, 1940, Serial No. 364,693

11, 1930, are examples,"a stable waterproofr and flexible abrasive articlein the nature of sandpaper and the process of lmanufacturing the Il same is described.

Such treatment and resulting product, though satisfactory, entails considerable expense, by reason of the time consumed and the time the necessary equipment is in use for producingsuch arti- 20 cles on a large commercial basis. v

It is therefore an object of our invention to provide an abrasive article comprising primarily, a flexible backing material in the nature of a felted fabric, such as paper. orfa woven fabric, such as cloth, as the base for a grit or layer of abrasive particles, and including a binder with or without sizing coats of a material that is waterproof, stable/and results in a nal article which is flexible and resists the action of fluids used 30 in abrading operations, and of a character to maintain the bonding effectof 'the abrasive article effective 'in dry or wet abrading operations throughout the effective abrading life ofi, the abrasive article, and which eiIects considerable economy in the production and cost of the article, by reason of the speed with which the article may be produced. It is contemplated by our invention to provide an abrasive article in the nature of sandpaper, including` as a component thereof, either as a binder, sizing coat, back coat or grit-sizing coat, a stable, flexible and waterproof material which acts more efliciently than such `components as previously known to us, so far as inertness, waterproofness, flexibility and eilciency in abrading operations are concerned, and which'entails considerable economy in labor and cost of production.

It is further contemplated as an object of our invention to provide stable, flexible and waterproof materialsv and methods oftheir production, for purposesparticularly valuable in the production of abrasive articles in the nature ofsand- Gil paper, wherein products characterized byinert- 55 ness in the presence of liquids used in abrading operations, together with waterproofness and iiexibillty, are obtained. f

In the practice of our invention. we have found that the resinous component ot the binder material may be substituted in whole or in part by a 5 phenol-aldehyde condensation'resin, such as a phenol-formaldehyde resin, and that, as a result ofsuch substitution the time required for the setting or hardening of the binder is materially reduced, thus permitting greater speeds of production. And in addition 4to this highly desirable economy of time we are able to improve the quality of the end product by the said substitution.

Furthermore. we have found that by proper selection and treatment of' the fatty-oil and phenol-formaldehyde resin we are able to induce a reaction and/or polymerization involving said ingredients, thereby obtaining aresinous material differing substantially from all similar materials known to us and possessing properties particularly desirable for our purposes. I

In a convenient form, the fatty-oil is preferably China-wood oil and the resin constituent -is a phenol-formaldehyde resin of theakelite type which is acetone and oil soluble and potentially reactive with fatty oils. The China-wood oil land the phenol-aldehyde resin are preliminarily treated to, induce polymerization. This is accomplished by melting the resin in the fatty-oil while the oilis receiving its heat treatment. The' reaction and/or polymerization of the phenolformaldehyde and the fatty-oil occurs at approximately 235 C.; and when natural resins or the 4 glyptal type of resins areto be incorporated into 35 the bond in addition to the phenol-aldehyde resin, the second resin is preferably .added after the aforementioned reaction has been carried to completion. We have found that the presence of anatural resin retards the reaction o to the degree that it is present within the limits of reacting'resin to combine with an acidic oil or resinous material, and under certain conditions, may, if not totally, partially inhibit the rer action between the oil andthe reactive phenolaldehyde resin, if present.V Driers do not appear to influence this reaction. However, we ilnd it convenient to add some drier after -'the heat treatment in order to accelerate the drying or hardening of any excess of the fatty oil which 'does not 50 enterinto direct combination with the phenolaldehyde resin. The driers may be of the type referred to in the' prior Okie U. S. patent; other driers such as the metallic resinates, particularly manganese resinate and/or tungate may be used.

The oil resin compound so prepared may have added thereto a .suitable `thinner 'inquantities dependent upon the use to be made of it, either for the binder coat or sizing coat. or dependent i o upon the condition of the backing material which may or may not have been previously waterproofed. By selecting the proper thinner or mixvture of thinners, land by controlling the amount added to the oil-resin compound we are able to obtain any desired degree of penetration into the backing material from complete saturation to a surface coating or lm of suiiicient thickness to'act as-the bindericoat for the grit or layer of abrasive particles. Thus we may add between 10 and 50% of thinner to the oil-resin compound described above.

The polymerized resin-oil and thinner compo- Percent China-wood oil about.. 62. 5 Phenolic-aldehyde resin about 25. 0

- Driers about-- .5 Thinners about.. 12. 0

The percentages above given are by weight.

.The thinner preferred by us is a hydrocarbon of the petroleum series, known on the market as oleum spirits, and has a' boiling range of 125 to 244 degrees C.; initial boiling point not below 40 '125 degrees C.; not more than 50% over at 171 degrees C.; recovery at leastv95%; residue 'colorless; and point below 244 degrees C. To a certain extent, petroleum spirit of a boiling range between 60 and 120 degrees C., specific gravity ,67 to .70 may be used. Also varnish makers and painters naphtha may be used. This product has a boiling range of 100 to 160 degrees C.; specic gravity .73. White spirit may `also be used which. is a petroleum hydrocarbon having.

e boiling range or 80% below 19o degrees c.; 90% below 200 degrees C. Lacquerpetro may also be used which' is a hydrocarbon solvent of the petroleum series: 85% distilling below -200'degrees C.; 97%A distilling below 220 degrees C.

Where the raue or the-resin te the on is greater than 1.-3, either turpentine or solventl naph'tha (coal tar solvents) must be used as the major part of the thinners. Wherethe ratio isi-3 or less, oleum spirits maybe used. Additionally, the thinner may be a mixture of `turpentine and the' hydrocarbon solvents above enumerated.

'As `the resulting oil-resin compound, as contemplated by us and above described, has certain oxidation properties indicating :a portion of the drying oil to retain some of the drying .characfir terlstics, the thinner as contemplated by our inyention is onewhich has solvent action upon the oil-resin to retain a homogeneous mixture through all stages of separation of the thinner, in accordance with the further treatment to which the article is submitted in its production. The composition as prepared by our invention is "applied to a backing material. either by surface coating or an impregnation, when a layer servingashthe binder coat isapplied. The grit or layer of abrasive particles is incorporated in 'a surface coating upon the backing material, in

accordance with processes heretofore devised-for incorporating the same upon the web-of fabric` s prepared, forms a film which is dust-free,'that is,

a .ihn to which dust will not readily adhere, in go fifteen minutes and can easily be handled in one hour.

The particular features of our invention thus far described, distinguishing from the waterproofing ingredients used in said prior Okie patg5 ents, reside in the production of a film which is equally flexible, but of tougher and harder characteristics. all liquids which maybe used in. abrading oper-'-V ations, such as water, oils, solutions of detergents 30 and gasoline. The period for setting ordrying the nal product is materiallyI reduced. As com-4 ,i pared with i articial resins, such .as phenol. formaldehyde condensation resins of the Bakelite type, our composition is productive of greater 35 speeds of operation and produces a tougher, more flexible product, and for substantially thick binder coats without n ecessitating rigid backing forms, molds and/or pressure to react the -product to its final form, and such reaction tothe o final stage is accomplished without rigid backing forms, molds, the nal setting being attended with no warp'ing or distortion of the fabric carying the binder. As a further embodiment of our invention it is '45 contemplated .by us to preliminarily heat the drying oil with the drier, short of forming a solid product and then incorporate thev proportion of the phenolic-aldehyde resin, preferably the potentially reactive type, incorporate this mixtures@ with the necessary quantity of thinner and then surface applythis mixture to the backing material, in accordance with the sandpaper making processes previously described. It is Ipreferred under such conditions, to substitute the phenollc- 55 resinous composition for only part of the resinous constituents specified in said Okie patents, and

where a non-oil-soluble phenolic resin isfused, preferably preliminarily fusing the resinous constituents which may be used withthe phenollc- 30 aldehyde resin, before incorporation into the vegetable fatty oil used. i

l In the embodiment above referred to, we have referred to the use of a phenol-aldehyde condensation resin of the Bakelite type which is 55' acetone and oil-soluble and/or reactive with fatty oils, as the most suitable form of the resin which may be substituted in whole or in part for the resinous constituents in` the formulae' referred to, of the Okiev patents. A still more particular des- 70 lgnation .i of the phenol-aldehyde condensation resin will now be made. In the production of an acetone and oil-soluble resin and one which is The iilm is substantially vresistant to v n and after reaction asydescrlbed-and formation of 20 to 80 parts of tung oil are dissolved with 100 parts of a phenol. conveniently cresci.- To this is added about 3% of a converting agent, using aluminum chloride, sulphuric acid or hydrochlo-n d ric acid. These ingredients are reacted to condensation and any aqueous material formed is thereafter separated. The oily layer has then added to it a sumcient quantity offormaldehyde to ordinarily combine with the phenol constituent to form a non-reactive resin. About 65 parts of formaldehyde are usually added. Additionally. after partial reaction sufficient to form a permanently fusible resin, there may be added an additional quantity of formaldehyde, or a matel5 v rial having an active methylene group, such asnexametnylenetramine to make. under the heat treatment, and \oil reactive reslnousmaterial.

The resinousumaterial mayV be substituted in whole or in part in the Okie formulae heretofore referred toand comprising 12 to 39% of resinousl materials; fatty oil from 8l' to`50%:-driers from .5 to 1% and the balance up to y40% of volatile Indistinguishing our foregoing form of acetone and oil soluble and/or fatty oil reactive resin .resin last described, 'which isa convenient onefor our purposes. as the phenol-fatty-oil-reactive resin."v which is so termedby clear evidence of reaction, which takesplace when this resin is .heated with the fatty oil hereinbelow described in the furtherproducti'on of the binder material, as distinguished from mere increase in body vof the mixture with' other resinous materials. not-Q 85 withstanding Polymerization of the fatty oil itself.

As Vanother embodiment of an acetone and oili 'so In the ,preparation of the oil-somme aad/or oil-reactive reslnous material, utilizing the alkyl substituted phenol, these `ingredients may besubstltuted for the phenol.v Where the reaction is with an aldehyde, it is convenient tov react the 65 alkyl substituted phenols'and aldehydes inequal mol ratios with the usual condensing agents.

In the furtherproduction of the binder matev rial of the waterproofing composition. for our purposes, theV "phenol-fatty-oil-reactive resin" 'eo just'descrlbed 1s mixed witnthe proportion offatty oil'and drier, and heated in accordance with the process heretofore described, at a tempera- -ture of about 225 to 250 degrees C. Thereafter, the percentage of thinner is'added. g

While we have referred to substitution in whole or in partof the phenol-aidehyde resin for'the resinous component inthe formulae outlined and included by the Okiepa'tents. where'we use the re'sinous material hereinbefore' referred to as the phenol-fatty-oil-reactive resin." it lis preferred by us to have this resinous constituent entirely replace the resinous constituent of the Okie for- .mulae previously referred to. In making such complete substitution for the' resinous material coatings thus formed which -we may use, reference will be made to the 'recinto l 3 the oil-resin complex in the volatile thinner, the solution of the polymerized oil and "phenol-fatty-oiireactive resin may be used for the making" coat. binder coat or sizing coat in the production of a tough and with greater speed of production than heretofore known, and where this complex of poiymerized oil and phenol-fatty-oll-reactive resinls used;

the product not only-retains a homogeneous mixture through all stages of separation of the thinner. but also. forced drying of high order may be practiced, without fear of segregationof any portion of the resinous constituents. After elimination of the thinner, the web land coating or are submitted to air-drying action, preferably at elevated temperatures of 120 to 180 degrees F., as heretofore described.

The phenol-fatty-oil-reactive-resin and oil will react in all proportions of .-resln to oil, and

hardness of the finally reacted mixture may be increased with the increase. of the phenol-fatty oil-reactive-resln. The increase in hardness is more abrupt up to the point of three parts of oil to one part off resin. As the proportion of resinV to oil is increased beyond this point, the increase in hardness is more gradual. At approximately' the ratio of three parts ofoil to one part of resin, the reacted mass shows substantially greater toughness and greater hardness than the same -quantity of resin in an` unreacted form.. This 80 serves not only as a basis for evidence of reaction of the resin and the oil, but also as a guide to alteration of the propertieaof the nal prod'- uct with thevariations of the ratio of oil to resin.

` In the convenient practice immediately abovevs' referred to, wherein the phenol-fatty-oil-reactive-resin is completely substituted for the resinous constituents of the Okie formulae, thereby completely eliminating the natural resins, any f tendency towards segregation of' the resinous l-rnaterials is completely avoided in all stages o f separation of the volatile thinner or' relative speeds of separation of saidthinner, resulting in 'an exceedingly homogeneous end product of ascertainable uniformity without the retention of considerable saponiilable. constituents, and therefore rendering the product more adhesive in the .presence of abrasive particles, and in general,

giving, a product of -greater waterproofness; greater hardness to resist displacement of .such particles. or penetration of the binder by abraded particles, and greater .toughness to permit higher speed abrading operations.

As hereinabove pointed out. a convenient form ofour binder or adhesiv ate'rial may comprise 55 substantially two and on `half to three parts of China-wood oil to'one part of phenol-fatty-o'ilreactive-resin."` This substance. is highly watery proof and forms a very strong, tough bond of good .flexibility and a fair degree of stretch. o0 For some 'purposes we have found the stress of stretch or distensibility of this binder to be somewhat 4tuo great, particularly where paper is used asa backingmaterial in an abrasive article which is used in water abrading operations. es The stress of v'stretch or distenslbil-ity of the binder coat being greater than that of the moist paper backing may cause the latter to develop cracks while the abrasive article is in use, thus putting the entire stressof the abrasive operation on the'binder coatingnand thus reduce the life of the abrasive article.'

We have found that this dimculty may be overcome by adding a quantityof 'glyptal type of the resin-fatty-oil compound hereinbeins are not without some modiication. as desirable for our purposes as others herein'particuproper proportions. Forms ofthe glyptal reslarly described, we have' found -,that any gly'ptal resin which -is miscible with fatty-oils or oil varnishes, and particularly those which include the fatty acids of drying oils or semi-drying oils, obtains the desirable results when used in the -tion is then heated to 210 degrees centigrade for a time and nally to 225 degrees centigrade until the evolution of gas decreases. In the above cited example of a glyptal type resin, especially one which is miscible with, or

` Minnesota Mining and Manufacturing can be blended with, fatty oils, such as that con^ templated by us in making 'a vphenol-fatty-oilreactive-resin," and oil complex, the resins or resinous compositions, such as that made in ac cordance with the application of Guth, Serial No. 347,159 entitled Flexible sheet abrasive and method of making the same, and assi ed'to the my, may be utilized by us in accordance with the present invention. \Thus, the glyptal resin may be made from DOlyhydric compounds of the character disclosed in said application, together with aromatic or cyclic polybasic acids, and though the phthalic'anhydride may be used as a single aromatic acid, this maybe substituted in whole or combined with an aliphatic acid, such as oleic,

butyric, succinic, citric, also benzoic, maleic, -glutaric, suberic, camphoric, adipic,` linelic, eleosteanic,`lineoleic, linolenic. The acids above listed derived from' drying-oils are preferred by us and the lineleic, linelic, linolenic, and eleostearic acids of the lgroup enumerated are characteristic of acids derived from drying oils. which are so preferred.

where Suu greater nezdbiuty is desired, saperle.l and adipic acids may be included as the resinifying carboxylic, organic acids. in addition to the drying-oil fattty acid above enumerated, and as partial or entire replacement for the phthalic anhydride in the example above given.`

= 74 parts er -phtneue anhydride and As a variation for the production of an oil miseibie er en soluble glyptei type resin, the m1- lowing may be given:

Example' B` 92partsofglycerine" .N' L 296 parts of phthalic anhydride. These ingredients are heated to degrees Ca, after which there isadded l 140 parts of a fatty acid derived from a drying oil, such as China-wood oil, linseed oil, Perilla oil.: Thse constituents are heated from 2l0 degrees C. until evolution of the gas decreases and resincation has been effected. As a variation in the production of an oilsoluble glyptal type resi, which is compatible to the oil contemplated in accordance with our infattyoil-reactive-resin aasoad -fere described. while some of' the giypcai rervention, as well as to the phenolfatty-oi l-reac tive-resin, for the purposes above enumerated in connection with forming the binder coat. or for a separate and distinct coat compatible with the "phenol-fatty-oil-reactive-resin China-wood 5 Another example of glyptal type ofresin which 15 we have found valuable for reducing the stress of stretch of the binder as described, particularly where paper is used as a backing material'for anabrasivearticle,asanadmixturewiththe` and fatty-oil compound, or as-a separate compatible coating formingthe sizing for the paperbacklng or asasadsize for the grit bonded coating, a complex or blend of a glyptal resin and China-wood oil may be preparedas follows:

Example D A glycerol phthalic anhydride resin and Cinnawood 'oil in the proportions of equal parteci the .-resinvand oil'are dispersed in a high boiling solvent, such as benzyl benzoate. The mixture is heated to 100-110 degrees C. until the Chinawood oli thickens and then heating is continued at 200 degrees C. until the glyptal resin and China-wood oil become dispersed or form a ocm plete blend. The solvent is removed by precipitating the resin in a non-solvent .for the resin. In this example, other oils than China-wood oil may be used, such as linseed oil, Perilla oil, soya bean oil, castor oilI cotton seed oil. Other high boilingdispersing agents may be used and the 0 gly'ptal resin may be used in its linitial resinified stage.

We may also use an artiiicial vresin complex of the condensed ester type and phenol-aldehyde accordance with the procedure outlined in the ,Guth application aforementioned, and these may .the use of a dispersing 'agent and in this form may be used as an addition to the .phenol-fattyoil-reactive-resin and fatty-o compound for reducing the stress of stretch and for the purposes contemplated by us as previously described, in forming a coating compatible withthe phenolfatty-oil-reactive-resin and fatty-oil compound which may be used.

As an additional example of a'phenolealdebyde glyptal type of resin which may be made for the purposes contemplated by us, the following example may be given:

Example E A phenol, preferablycresylic acid and an aldehyde, preferably paraldehyde, in equal molecular proportions, are heated until a primary oonden- 15 type, in which drying-oil acids are included in 45 sation is obtained. After purification` to remove the imreaoted cresci, there is added 45 parts of piithalic anhydride: 22 parts of glycerol;

2s para of unseen ou acids. These ingredients In the example above given, for cresyiic acid land paraldehyde, the phenol type resin may include phenol-aldehyde', cresol-furfurai, phenol-,ketone types of resins or resin forming ingredients.

As an additional form 'of oil-soluble resin of the glyptal type, which may be used in association with thev fatty-oii-reactive resin and fatty-oil j compoundfor Athe purposes indicated, this may be one resulting from forming a phenol type of resin in the presence of a natural esteriilable resin,

Example F 250`parts of rosin;

.parts of cresol, are melted with 8 parts of paraformaldehyde.. 'Ihese ingredients are fluxed successively at 1 00-125 devgrees C. and 220 to 250 degrees C.

25 parts of an esterifying ingredient, such as glycerine, is added and heated toeause esteriilcation by heating to 275 degrees (J.V Additional '4 quantities of a polybasic acid, such as phthalic 40 anhydride and glycerine are added and then heated, preferably in an atmosphere of'carbon dioxide at 200 to 240 degrees C' to form the'glyp' i f the foregoing resinous mixtures, as enumerated .tal type resin in the presence of the phenol resin esterifled natural resin mixture.

a"compatible resin having glyptal resin characteristics, forv the purposes contemplated byus, the

following additional example maybeivnf -MmpleG obtained. The resulting resin may be further reacted with a phenol type of resin, which is oil- As astilL'further embodiment for the production of an. alkydor glyptal type of resin, compatible for the purposes ihereinbefore described, the 'following additional examples may be given:

Example H p iso parts or slycerine; 280 parts of drying-oil acid.

' The above ingredients are heated to a temperal ture of 200 degrees C. for approximately one hour.

To the mass so heated, there is added: 290 partsof phthalic anhydride,v

during reaction of the previous reacted ingre-- dient, the being maintained at 200 to 220 degrees C. for a further period of apthe natural resin being esteriedand the glyptal x As a still further example for the production of i soluble, whichremotes the solubili of the p t-y desired degree of stretch and flexibility in the nproximately two hours. The resin so formed will be oil-compatible. J

As noted, reaction is first accomplished between the polyhydric alcohol andthe dryingcil acid. before the addition of the acid which may be l phthalic anhydride or the 'polybasic or aromatic acid.

Where glycerol is speciiied, other polyhydric alcoholsmay be used, such as glycol-diethylene glycol and similar polyhydrlic alcohols. l.

A still further example of an oil-compatible alkyd orglyptal type resin may be made as followszf Example I 7 0 parts phthalic anhydride.' 44 parts linseed oil acid or other drying-oil acids; 35 parts slycerine; 40 parts coumarone resin.

The above ingredients are heated at a temi. perature of 250 degrees C. for approximately two and a half hours, after the temperature stated has4 been attained. l

The foregoing procedure may be varied tothe. extent that after forming the' resin from the s' phthalic anhydride, glycerine and drying-oilfatty acid,'as described, the oil-soluble phenol type of resin that may be used is that which is hereinabove described as the "phenol-fatty-oil-reactive resin. v f ,l

In the examples enumerated under A to G, though we have described a cial resins .of the condensed ester type, lwhich include in addition tothe polyhydrie alcohols, resin'ifying carboxylic organic acids or their anhydrides, preferring such 3.

v'resinifying carboxylic organic acids, in certain inunder Examples A'toI and the variations in procedure outlined thereunder, `'reference will be 4| madeto these compositions as "oil-compatible glyptal' resins. L

We have previously stated that the addition ofthe "oil-compatible glyptal re to the phenolfatty-Qilreactive-resin 'and fatty-oil compound l is exceedingly desirable, particularly in connection with the' use of the binder for coating a backing materialof paper in theformation of an abrasive article, and while we are not prepared to state exactly the physical or chemical function I which the oil-compatible glyptal resin performs in our composition, such addition, in eect, reduces the stress of stretch and renders the binder moreV retentive ofits exlbiiity'. We obtain the n `ished binder by adding an oil-compatible glyptal resin to an extent of approximately 3 to 35%; preferably approximately 10% of" the phenolfatty-loil-reactive-resin and fatty-oil compound. t' While we mayblend the oilfcompatiblejglyp- 0l tai resin" wiuii the "phenoLr'atty-ou-reaetiveresin or the China-wood oil compound,or the mixture of the phenol-fatty-oil-reactive-resin. and 'China-wood oil compound,` before polymers. izing the phenol-fatty-oili'eactive-resin and 70 China-wood oil compound, we prefer to rst POIymerize the "phenolfatty-oilyreactiveresin and China-wood all 'to obtain the reaction or polymerization at the temperature of about 225 to 4250 degrees C., and after reaction or -polyglyptal resins.

ticularly those enumerated under Examples A to.

G, which include a. phenolic constituent, may

serve-completely to displace the phenol-:fatty 'oil-reactive-resin hereinbefore specically described, in which embodiment the Oil-compatible glyptal res and the China-wood oil or'similardrying-oil -is reacted or polymerlzed, preferably in conjunction with an agent to induce `polymerization or reaction. Such complex of oil-compatible glyptal resin and oil, when polymerized, in accordance with this procedure, provides a product which, though including the fatty-oil in percentages of Sli-81% ofthe total mas's, produces a lm which dries rapidly.

'I'he binder compound described above, which includes the fatty-oilgreactive-resin," drying-oil land "oil-compatible glyptal resin, is particularly suitable as a. coating for the lighter grades of paper, for example those umn-ing from to 50 pounds per ream, when this paper .isV used as a backing material in. the preparation of sand-- paper. i For the purpose of illustrating the constructional features of the character above referred .to and others contemplated by our invention,

reference will be made to the accompanying drawing in which Figures l-5 are sectional views through sandpaper, showing the backing and at-` Itach'ed layers. 1 The embodiment illustrated in' Figure 1 .is

preferably that construction previously referred to in making lighter grades of sandpaper. In Y' this view .a sheets crrelanveiy light paper is provided with a coating 6, comprising the binder hereinbefore described and 'which contains a quantity of the glyptall resin. The .coating so provided penetrates partly into the backing, asshown at 1, and into this binder coating 6, while still plastic, there is provided agrit layer 8 of abrasive particles. r

Where heavier grades of paper are used, good results are obtained b y applying a glyptal resin, such as Rezyl 1103, directly to the paper as a pre-sizing, .though this pre-sizing coat may be any other of the aforementioned "oil-compatible When this coating'isformed and partially or completely set, there is applied the binder coat comprising the phenol-fatty- -oil-reactive-resinf China-wood oil reacted composition. During .the maturing of the binder coat, suflicient interiusion takes place between the glyptal resin'sizing coat and the binder coat so that the ilnished bond is strong and .-tough, and possesses vthe proper degreel of stretch to prevent cracking or breaking .up of either the paper backing or the `bindervcoat.particularly c' during rigorous liquid abrading operations.` w

vIn ,Figuresl the paper sheeting I0 of a relatively heavy grade is given a presiz'ing coating II of a glyptal resin, such asRezyl 1103 or any other oil-compatible glyptal resin hereinbe -fore described. 'This coating partially pene-S- trates the backing I0 in the manner shown 'at I2. After partially or completely setting this sizing coat I I, we apply over the sizing coat a binder coat I3 and grit I4. The coating Il is preferably a "phenolkfatty-oll-reactiveresin" and oil composition treated in accordance with the process heretofore described and penetrates presizing coat I1 is preferabl'yan oil-compatible 'land/or homogenizes with the pre-sizing coat Il,

as shown at I5..

While the provision of an oil-compatible glyptal resin as a sizing coat in connection with a binder coat I3 o phenol-fatty-oil-reactive t5A resin and oil is the preferred form, 'for the heavier grades of abrasive material, the inclusion in the binder coat composition I3 ofsmall amounts of oil-compatible glyptal resins blended therewith, also forms an exceedingly desirable binder coat composition.

In Flgure we have illustrated a variation in construction for forming the various layers of abrasives in the nature of sandpaper of the character illustrated in Figure 1 but with an additional application of a sand-sizing layer 9. In this embodiment, the binder layer' l may comprise the mixed complex of phenol-fatty-oil-reactive-resin" and China-wood oil-reacted ccmposition containing a quantity oi' oil-compatible 20 "binder coat I8 may comprise oil-reactive-resin and fatty-oil-reacted composition, with or without reacted-oil-compatible glyptal resins. -The f 35 glyptal resin, and for purposes of compensating for any distortion andotherwise improving the .back surface of the paper, the back-size 20 may also befor'med of a coating of the same material as the presizing coat. Where the binder coat I8 4o comprises essentially an oil-reactive-resin and iatty-oil-reacted composition, the back-sizing.

lmay also be m'adeof a coating of this'same com- Y position. v Y

H'nFlgure 5 there is illustrated a sectional view through sandpaper, essentially the same as in .Figure 4, except that there isv additionally gapplied a sand-sizing coat 2l. Where the binder' coat is essentially an oil reactive resin and fattyloil-reacted composition, en oil-compatible glyptal .fresin coating may constitute the sand-sizing coating 2 l.. Preferably, however, the sand-sizing coating 2| lconstitutes an oil-reactive-ren-fatty oil-reacted composition, where the binder coat ,I8

includes an oil-reactiveresinjand iatty-oil-re- .acted composition together withan oil-compatible glyptal resin, or is essentially'an oil-compatible glyptal resin which, under certain circume tsances, mayentirely constitute the'binder coat This application is a continuation-impart of our prior filed application S. N. 660,319, filed March 10, 1933, andis a division of ourapplication -Serial No. 708,662, led.January 2'?, 1934.

' Having thus described our invention and illustrated its use, what we claim {s new. and desire to'4 secure by Letters Patent is: L

l. An abrasive article comprisingan undlstort- 'ed compositev of a sheet of backing material and a grit or layer of abrasive particles bonded thereto by a binder layer including a phenol-fatty-oilreactive-resin and an oil .compound having added thereto a glyptal type of resin for increasing and retaining the exibility thereof. f

. 2. An abrasive article comprising anundistort- 75 ed 'composite of a sheet of backing material and a grit or layer oi' abrasive particles bonded thereto by a binder layer including a phenol-fatty-oilreactive-resin and a material for increasing the flexibility` thereof, comprising a glyptal type of resin and an oil with which said glyptal type of resin is miscible. Y

3. An abrasive article comprising an undistorted composite of a. sheet of backing material and a Agrit or layer of abrasive particles bonded thereto by -a binder layer including a phenol-fatty-oilreactive-resin and a material for increasing the riexibility thereof, comprising a glyptal type oi' resin-fatty oil acid compound.

4. A iiexible abrasive article or sandpaper especially adapted for wet sanding operations comprisirg a flexible, base coated with particles of abrasive embedded in a water-resisting binder fiayer comprising a phenol-fatty-oil-reactive-resin and a lesser but substantial proportion of an oilmodii'led glyptal or allwd resin `for increasing the exibility of the saidphenol-fatty-oil-reactiveresin. A

5. A exible abrasive article or sandpaper especially adapted for wet sanding operations comprising a exibie base coated with particles of `abrasive embedded in a water-resisting resinous composition comprising anintimate intermixture of an oil-soluble glyptal or alkyd resin with a phenolic resin material produced by cooking together a phenol-aldehyde oil-reactive resin with a drying oil.

6. A exible abrasive article or sandpaper especially adapted for wet sanding operations comto the extent of 'at least three percent of said f binder.

7. A flexible abrasive article or sandpaper especially adapted .for wet sanding operations com-v prising a iiexible base coated with particles of abrasive embedded in a binder consisting substantially of a water-resisting resinous composition comprising an intimate intermixture of an oil-compatible glyptal or alkyd resin with a phenolic resin material produced by cooking together `an oil-soluble phenol-aldehyde resin with a drying oil. said alkyd resin being present in lesser proportion than said phenolic resin and' making up from three (3) to thirty-live (35) percent of the combined said phenol-aldehyde and drying oil of the saidbinder.

8. A ilexible coated abrasive article especially' adapted for wetsanding operations comprising a ilexible base coated with particles of abrasive embedded in a water-resisting resinous binder composition comprising an intimate intermixture4 of an oil-soluble glyptal o r alkyd resin'with a phenolic resin material, produced by cookin'g together an oil-solublephenol-aldehyde resin withl a drying oil and, while the mass is still hot, mixing said alkyd resin therewith and allowing the whole to cool, said drying oil being employed in excess of said phenol-aldehyde resin. i Y

9. A exible-backed abradant comprising a iiexible base coated with particles of abrasive emhomogeneous resinous composition produced by cooking together an oil-soluble phenol-aldehyde resin with a drying oil and, while the mass is still hot, mixing uniformly thereinto an oil-compatible alkvd resin and allowingthe whole to cool, said alkyd 4resin being introduced to the extent of at least ten (10) percent oi the said phenol-aldehyde resin and drying oil combined, and said drying oil being employed to the extent of two and one-half Y (2i/2) to three (3) parts thereof'to one-(1) part of the said oil-soluble phenol-aldehyde resin.

l0. A flexible-backed abradant comprising a ilexible base coated with particles of abrasiv ein-V bedded in a water-resisting resinous compos tion `which is the hardened uniform product resulting from combining and reacting at superatmospheric temperatures an intimate admixture of an oilsoluble phenolic resin with a. lesser but substantial proportion of a drying-oil-modiiied alkydresin.

,bedded in a binder comprising a water-resisting, Y

RICHARD PAUL CARLTON.

BYRON J. OAKES. 

